1. Field of the Invention
This invention relates to a device for collecting solar energy and more particularly to a device operatively associated with a roof of a building for obtaining an electric energy and thermal energy at the same time from the solar energy.
2. Prior Art:
Extensive research and development efforts have been made for the realization of the technology of making effective use of solar energy, i.e. to derive therefrom electric energy in a manner as disclosed for instance in Japanese Utility Model Laid-Open Publication No. 60-170433 and thermal energy as is known from Japanese Utility Model Laid-Open Publication No. 55-32911. To the best knowledge of the present applicant however, no useful technology has yet been made available for successfully deriving both electric and thermal energies at the same time from solar energy. This is mainly due to the following reasons.
Solar batteries in common use mostly rely on the use of silicon elements, and the output of such silicon batteries disadvantageously declines with an increase in the ambient temperature. Therefore, in the case where the solar batteries are installed in the roof tiles as proposed in the aforesaid prior publication, it becomes necessary to provide thermal insulation for the roofing. On the other hand, when converting the solar energy into heat energy, it would be a great advantage to form the roofing with highly heat-conductive material, in which instance, however, it would still be necessary to provide proper heat-insulating means so as to prevent possible adverse effect of heat upon the interior of the building or house. There is thus a technological contradiction in the attempt to efficiently derive electrical and thermal energies at the same time from the same source of solar energy.